The program is concerned with the basic events taking place at the cholinergic receptor and consists of projects focused on the reactions involved in the activation of the receptor and its subsequent restoration to the resting state. In the first project, a group of recently derived thermodynamically valid ion exchange equations will be applied to the analysis of the exchange reactions between potent ligands and the bivalent inorganic ions on particulate preparations of the receptors and also to the exchanges between the organic ligands themselves. In the second project, a new synthetic curariform compound, osmarine, containing two osmium atoms will be used to study the electron microscopic ultrastructure of the receptor arrangement. In the third project, the transmembrane transport of decamethonium will be used to determine the relevant equilibrium constants in isolated voluntary muscle. BIBLIOGRAPHIC REFERENCE: Dermont B. Taylor, Kenneth P. Callahan and Iqbal Shaikh. "Synthesis of a bifunctional coordination complex of osmium with curariform activity". Journal of Medicinal Chemistry, 18:1088-1094, Number 11, 1975.